[vlc-devel] [PATCH 1/2] Add helpers for unsigned integer overflow

[Thomas Guillem]

On Sun, Nov 12, 2017, at 13:44, Romain Vimont wrote:
> 
> 
> Le dimanche 12 novembre 2017 à 11:27 +0200, Rémi Denis-Courmont a écrit :
> > ---
> >  include/vlc_common.h | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 114 insertions(+)
> > 
> > diff --git a/include/vlc_common.h b/include/vlc_common.h
> > index ed5ff77730..e3d7086ff7 100644
> > --- a/include/vlc_common.h
> > +++ b/include/vlc_common.h
> > @@ -661,6 +661,120 @@ static inline uint64_t (bswap64)(uint64_t x)
> >  #endif
> >  }
> >  
> > +/* Integer overflow */
> > +static inline bool uadd_overflow(unsigned a, unsigned b, unsigned *res)
> > +{
> > +#ifdef __GNUC__
> > +     return __builtin_uadd_overflow(a, b, res);
> > +#else
> > +     *res = a + b;
> > +     return (a + b) > a;
> 
> (a + b) < a
> 
> > +#endif
> > +}
> > +
> > +static inline bool uaddl_overflow(unsigned long a, unsigned long b,
> > +                                  unsigned long *res)
> > +{
> > +#ifdef __GNUC__
> > +     return __builtin_uaddl_overflow(a, b, res);
> > +#else
> > +     *res = a + b;
> > +     return (a + b) > a;
> 
> (a + b) < a
> 
> > +#endif
> > +}
> > +
> > +static inline bool uaddll_overflow(unsigned long long a, unsigned long long b,
> > +                                   unsigned long long *res)
> > +{
> > +#ifdef __GNUC__
> > +     return __builtin_uaddll_overflow(a, b, res);
> > +#else
> > +     *res = a + b;
> > +     return (a + b) > a;
> 
> (a + b) < a


Ooops, fixed now (this helper is still not used).
Thanks for the review.

> 
> > +#endif
> > +}
> > +
> > +#ifndef __cplusplus
> > +# define add_overflow(a,b,r) \
> > +    _Generic(*(r), \
> > +        unsigned: uadd_overflow(a, b, (unsigned *)(r)), \
> > +        unsigned long: uaddl_overflow(a, b, (unsigned long *)(r)), \
> > +        unsigned long long: uaddll_overflow(a, b, (unsigned long long *)(r)))
> > +#else
> > +static inline bool add_overflow(unsigned a, unsigned b, unsigned *res)
> > +{
> > +    return uadd_overflow(a, b, res);
> > +}
> > +
> > +static inline bool add_overflow(unsigned long a, unsigned long b,
> > +                                unsigned long *res)
> > +{
> > +    return uaddl_overflow(a, b, res);
> > +}
> > +
> > +static inline bool add_overflow(unsigned long long a, unsigned long long b,
> > +                                unsigned long long *res)
> > +{
> > +    return uaddll_overflow(a, b, res);
> > +}
> > +#endif
> > +
> > +static inline bool umul_overflow(unsigned a, unsigned b, unsigned *res)
> > +{
> > +#ifdef __GNUC__
> > +     return __builtin_umul_overflow(a, b, res);
> > +#else
> > +     *res = a * b;
> > +     return b > 0 && a > (UINT_MAX / b);
> > +#endif
> > +}
> > +
> > +static inline bool umull_overflow(unsigned long a, unsigned long b,
> > +                                  unsigned long *res)
> > +{
> > +#ifdef __GNUC__
> > +     return __builtin_umull_overflow(a, b, res);
> > +#else
> > +     *res = a * b;
> > +     return b > 0 && a > (ULONG_MAX / b);
> > +#endif
> > +}
> > +
> > +static inline bool umulll_overflow(unsigned long long a, unsigned long long b,
> > +                                   unsigned long long *res)
> > +{
> > +#ifdef __GNUC__
> > +     return __builtin_umulll_overflow(a, b, res);
> > +#else
> > +     *res = a * b;
> > +     return b > 0 && a > (ULLONG_MAX / b);
> > +#endif
> > +}
> > +
> > +#ifndef __cplusplus
> > +#define mul_overflow(a,b,r) \
> > +    _Generic(*(r), \
> > +        unsigned: umul_overflow(a, b, (unsigned *)(r)), \
> > +        unsigned long: umull_overflow(a, b, (unsigned long *)(r)), \
> > +        unsigned long long: umulll_overflow(a, b, (unsigned long long *)(r)))
> > +#else
> > +static inline bool mul_overflow(unsigned a, unsigned b, unsigned *res)
> > +{
> > +    return umul_overflow(a, b, res);
> > +}
> > +
> > +static inline bool mul_overflow(unsigned long a, unsigned long b,
> > +                                unsigned long *res)
> > +{
> > +    return umull_overflow(a, b, res);
> > +}
> > +
> > +static inline bool mul_overflow(unsigned long long a, unsigned long long b,
> > +                                unsigned long long *res)
> > +{
> > +    return umulll_overflow(a, b, res);
> > +}
> > +#endif
> >  
> >  /* Free and set set the variable to NULL */
> >  #define FREENULL(a) do { free( a ); a = NULL; } while(0)
> > -- 
> > 2.15.0
> > 
> > _______________________________________________
> > vlc-devel mailing list
> > To unsubscribe or modify your subscription options:
> > https://mailman.videolan.org/listinfo/vlc-devel
> _______________________________________________
> vlc-devel mailing list
> To unsubscribe or modify your subscription options:
> https://mailman.videolan.org/listinfo/vlc-devel